LX SFP not working in shared port

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Just purchased a new X440 - G2 switch and Extreme 1GB LX SFPs.  I am not able to get the SFPs to work in the shared ports (using port 47/48).   Is there something I need to do activate those ports to work with the SFPs?  I've tried different Single Mode patch cables as well as different ports/switches on the other end.  I know those have worked in the past.   Ideas?  ALso, can I plug these SFPs into the 10GB ports on the back of the switch?

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Chris Youngblut

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Posted 1 year ago

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Jeremy, Embassador

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Hmm.. What if you do a show port transceiver information detail, what do you get for 47/48?


This command might work
configure ports 47 preferred-medium fiber force
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Chris Youngblut

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I get the following when I show port transceiver info:

47        31.59    -4.89    -inf*      8.30          3.29          N/A     


I ran the second command and still nothing.


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Brandon Clay, Escalation Support Engineer

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It looks like the RX power on that port is -infinity dBm, so nothing is being received. Have you tried swapping the fiber pairs on one end of the link? I suspect both optics may be transmitting onto the same fiber strand.
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Jeremy, Embassador

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I second that.  Just saw the reply... but your transceiver is working, because you can see the transceiver statistics.  As Brandon pointed out, the receive port is not actually receiving any light.  Swap them fibers and give it a try! 
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Chacko

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Hi Chris,

we had a similar problem with a x670-G2 after upgrading to 21.1.3.7.
We had to configure the speed settings manually (in our case 1G/Full).

Before updating, the auto-negotiation worked fine.
So you can try to hard-configure the speed settings.

Best Regards
Chacko
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Jeremy, Embassador

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Also, what is the transceiver you were using on the other side? The wavelength will need to be the same, for example both transceivers would need to be 850 nm
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Chris Youngblut

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Thanks for everyone's comments.  I found out that the Extreme SFP I was using was not compatible with the Cisco switch.  I thought I had checked that earlier but was mistaken.  Once I installed an SFP that was Cisco compatible, it worked fine.  I appreciate all the troubleshooting tips - they will come in handy in the future I am sure!